Acronym

An acronym is a word whose letters are the first letters of other words. People often create a short acronym that means the same thing as a much longer phrase (set of words). This is faster and shorter to say then the long phrase.

An acronym usually must be able to be spoken as word. Other abbreviations such as ASAP[1] (as soon as possible), USA[2] (the United States of America), ECU[3] (European Currency Unit), FBI[4] (Federal Bureau of Investigation), NBA[5] (National Basketball Association), NASA[6] (National Recovery Association or National Rifle Association) have combinations of letters that are not pronounced as a single word. People just say the letters, one after another.

These three-letter acronyms,[7] and some more obscure four-letter ones such as ISDN are more often called initialisms.

The word "acronym" comes from the Greek acro ‘extreme’ and onymus ‘name’.